Here are a couple of tips. If it is by itself look at it's face/nose. If it's more like a 2 litre bottle it's not a fawn. Next look at the body. From front legs to back legs, if it's rectangular shape it is not a fawn. A fawn will be square shape. Then there's the obvious, if it is with other deer just compare the sizes and take out the biggest one.

Don't worry about it, You'll know one when you see one. They got a mean look in there eye and that's no lie. Saw one a few years ago that looked like it had a dark mane like a lion. I'd like to kill that deer. She had a real attitude. This deer was a real educator, good for the herd, bad for the hunter.